Hi, I think you need to investigate that mass further to get an idea about its origin & nature. I am unable to comment about the line of management, as you have not provided much details about ultrasound
findings. There could be many differential diagnoses of a mass in that area, it could be related to your Crohn's disease or could be an entirely different entity. It coud be arising from bowel, urinary tracts/ kidneys, reproductive tract or from body wall. Any organ or tissue in that area could be the origin of that mass. Nowadays, CAT scan or an MRI
are considered better option for a diagnostic work up. Best of luck.